can just the ball joint be replaced and how?

 

Yep, just did mine. Went to Napa and got both ball joints for about $85. I removed the control arms myself. It's not the easiest thing in the world to remove/replace the ball joint itself. I got someone with a hydraulic press to do this for me. I also replaced the bushings with Energy Suspension bushings while I was at it ( http://www.courtesyparts.com/energys...on/maxima.html ). A hydraulic press and some kind of electric saw are also useful for removing the old ones.